Improvements of transient performance of pump turbine upon load rejection

Transient performance of the pump turbine having so-called S-characteristics upon load rejection can be improved drastically without causing transient reverse flow by optimizing control of the governor. Brief description of the improved control as well as some computer simulation studies to demonstrate the new control methods are presented. Possibilities for reduction of the penstock design pressure, minimizing the suction head margin against the water column separation and such construction cost saving effects are also discussed